Bladder type Well X Trol Water Tank (C) Daniel FriedmanWater Tank Air Pre-Charge Pressure FAQs
Questions & answers about the right air pressure setting for water tanks

  • WATER TANK AIR PRESSURE SETTING FAQs - CONTENTS: questions & answers about how to check and adjust air pressure in an internal bladder well water tank. Where to measure air pressure or water pressure on a water tank. Typical water tank actual draw-down volume vs. tank rated size. Questions & Answers on internal-bladder water pressure tanks. Well pump & water tank diagnosis & repair procedures
  • POST a QUESTION or READ FAQs about setting the air precharge pressure in internal-bladder type water pressure tanks

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Questions & Answers about setting the air pressure charge in a water tank that uses an internal bladder:

These frequently-asked questions answer "what is the proper air pressure setting for my water tank", "do I have to drain the water tank to add air", where and how to read the tank's air pressure, how to recognize that the bladder is ruptured or stuck, short on-off pump cycles and other water pressure, water pump, and water tank problerms that trace back to the water tank itself.

This article series describes how to determine the proper air pressure setting in a bladder-type well tank, when, and how to actually change the air pressure in the water tank. It describes how to determine the proper air charge for water pressure tank and how to adjust the actual tank air pressure to that number.

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Bladder-type Water Pressure Tank Air Charge Setting Questions & Answers

Photo of a water tank air valve for adding air to a water pressure tank

Question: how much pressure should be in the bladder tank for my water system?

2016/04/18 myra said:
I would like to know how much pressure should be in bladder tank

2016/04/19 ray said:

what should normal setting be on pump switch and comparetive preasure on air bladder


Sure Myra,


Set the air pressure in the empty water tank to 2 psi below the well pump pressure switch cut-in pressure. Bleed air pressure out of the water tank, or add air pressure into the water tank, until the tank pressure. For example, if your well pump pressure control switch is set to "cut in" (start pumping water from the well) at 30 psi, then set the pressure tank to (30 - 2) = 28 psi.



Question: short cycling well problems fixed by reading this article - thanks

Problem: Pump cycling every few minutes for months....Your question and answers solved my blatter type pressure tank cycling problem. I drained the tank and added air to 28 psi (was below 20 psi). I filled/pressurized tank and adjusted limits to 30 (low) and 50 (high). And WOW, now it takes 5 toilet flushings before pump kicks on. I tested the pressure tank psi after pump clicked off and my guage read 53 psi. So my problem was low air in the pressure tank and limits out of adjustment. Thanks for your instructions that anyone can follow and it saved me lots of money for a plumber. - Bob 8/21/11


Bob: Thanks for the nice note; we work hard to make our information useful and unbiased; I'm thrilled it worked for you; we continue to welcome questions or suggestions for our content as together we're smarter than working alone.

Other readers: See WATER TANK PRESSURE ADJUSTMENT for "how to" advice

Question: water pump is short cycling - I have no idea where to start

Ok so I have a few problems here. First off my pump is short cycling drastically as in I flush my toilet and within 3-4 seconds I hear the pump kick on. Second, when it kicks on it only stays on for a few seconds before turning off then it only stays off for a couple more seconds before turning back on.

And recently about once a day or once every couple days the pump wont come on at all and I have to go down and tap the pressure control switch housing for it to come on. By the time I realize that, we have pretty much lost all pressure in the house due to normal use. I haven't quite nailed down any tying reasons or times when this happens like my wife doing laundry or something along those lines.

When the pump is working we have plenty of pressure, almost too much (water sprays out hard and makes a mess when doin dishes lol). I have looked through this site and have found a bunch of useful information but am overwhelmed and don't have a clue where to start. Any guidance in this matter would be greatly appreciated. - Mark 9/23/11



you are describing a classic well pump short cycling problem. Eventually that condition can actually damage the well pump, resulting in less water pressure and flow than previously. You should be able to obtain satisfactory water pressure with the factory settings of your pressure control switch, typically 20/40 or 30/50 cut-in/cut-out.

I suspect that the reason you sometimes lose all water pressure under these conditions is that the rapid on-off cycling of the water pump is contributing to an overheating pump motor. Many electric motors include an internal thermal overload switch. When the motor is too hot, the switch turns off the motor. Later when the motor cools down on its own, the thermal reset switch resets and the pump will run again.

The rapid on-off short cycling well pump may also have led to burning on the contacts of the pressure control switch. That's why sometimes you have to tap the switch to get the pump to run. There could be other pressure control switch problems such as clogging of its pressure sensor due to debris in the water line.

Causes of pump short cycling are at WATER PUMP SHORT CYCLING

Procedures for replacing lost air in the water pressure tank (a common cause of short cycling pumps) are at WATER TANK AIR, HOW TO ADD

Procedures for adjusting or repairing a bad water pressure control switch are at WATER PUMP PRESSURE CONTROL SWITCH

Live links to those artilces are in the Related Links section near the top of this page.

Question: can't get water to drain out of the pressure tank

(Sept 17, 2015) Robert Ford said:
The statement:

Remove all water from the water tank. This means turn off the water pump, open a nearby plumbing fixture, run water until the water stops entirely - your water tank should be empty or close to empty.

Could be incorrect; If the bladder has failed and the tank becomes waterlogged (incorrect ration of air vs. water) you would only get a very small portion of the water to empty. If this was the case, one would need to force the rest of the water out via an air compressor. Ideally, you would draw water until the pump starts. Ensure that all faucets are turned off.Once it pumps up to pressure, cut the electric to the pump and close the gate valve between the pump and tank. Open a faucet to begin draining the tank.

Attach an air line from compressor to the air snifter valve. The compressor will then empty the contents of the tank. Once the last of the water empties it will begin to sputter (mixture of air and water). At this point, close the faucet and continue to add air until the proper pre-charge for the tank is met. This can be verified by a working pressure gauge or separate air gauge. Next, turn on the pump and open the valve going to the tank. If the well is old, this should be opened slowly at first. If the pump begins cycling on and off very quickly continue to open the valve further until the pump stays running continuously. This will help ensure the pump does not lose it's prime. If the system has a shut off valve between the tank and household lines it would be best to close this until the pump has full cycled and shut off.


Thank you for the comments, Robert, I've reviewed and clarified the article above, adding text on the effects of and dealing with a burst water tank bladder when adjusting the tank pressure or when draining a tank.

Watch out: But your actual advice and procedure as well as some of the terms you use are not quite correct and are actually dangerous and should not be followed.

At Please see WATER TANK BLADDER DIAGNOSTIC FAQs where I also include your suggestions and a detailed reply.

Question: do I have to drain the bladder-type water pressure tank before adding air to it?

(Oct 3, 2015) Steve said:
Just installed a new bladder tank and doni have to drain it first and add water then air back to it


Not if the factory precharge air pressure is correct for your system that is 2 psi below the pump cut in pressure

Question: Do I have to adjust the factory pre-set air charge in the water pressure tank?

(Oct 15, 2015) Anonymous said:
Just checking--looking to buy a new pump and pressure tank--most come now with factory presets. If the pump presets are 30/50 and the tank preset is 18 PSI--do I have to adjust the pressure in the tank to 28 PSI? or cna I leave the presets as is. Is it better to buy a pump and tank that have the same presets? any info you can provide would be great!!


I would set the -re-set pressure to 2 psi below the actual pump control switch cut-in pressure. So if your new switch cuts in at 30 the pre-set pressure should be at 28.

I suppose that as-delivered the pre-set pressure was set to 18 psi so that the tank would work OK with a pressure control operating at 20/40 psi.

If you leave the lower factory pressure the draw-down water volume from the tank will be less than optimal for your higher operating pressure range.

Question: check with a pressure gauge shows tank pressure is not what the factory said it would be

(Oct 25, 2015) Colin said:
Just bought a new pressure tank with the pre-set stated as 28 psi which is correct for my cut-in of 30psi. But a check with 2 pressure gauges shows it is 34 psi. I either accept the factory pre-set as correct and my gauges read high or my gauges are correct and I release air. 2 psi is not much of a margin-of-error. What will happen if the tank pressure is set above the pump cut-in?



Keep in mind that the air pressure you read at a water tank will be affected by temperature changes. If your water or tank are warm the pressure will be high.

I would go ahead and drop the pressure to 28 psi by your gauges.

If you set the air pressure in the tank above the pump's cut-in pressure with a tank using an internal bladder, ultimately the pump won't turn on.

In a tank that does not separate air from water by using an internal bladder, the excess air will simply blow out of nearby faucets and thus the problem will resolve itself.

Question: hole in the rubber sack inside my water pressure tank

(Nov 6, 2015) Larry said:
I just had my tank checked and the person told me that I have a sack inside my tank and it has a hole in it. If you shake the tank, you can hear the water inside. I just don't know if he is telling me the truth. I have good water pressure and am not having any problems. I am selling my house and I need to have my well inspected, so I don't know if this person is telling me the truth.


If the internal bladder ("sack") is perforated either the bladder needs to be replaced (possible on some models) or the entire tank needs replacement. Ultimately if don't replace it the pump will short-cycle on and off and be damaged or ruined.

Question: pump runs every time we turn the water on, water came out of the air valve on our tank

(Nov 22, 2015) Marge Windsor said:
I have a water tank that is 30/50 psi and it is turning on and off every time you turn on the water. I checked the air pressure to see what it was in the bladder and water came out of the valve. Is this normal or not


The tank is waterlogged and if it's an internal bladder type tank the bladder is damaged, perforated, or burst.


Question: tank shows no pressure and pump keeps turning on and off

(Dec 12, 2015) jeff said:
if my tank does not have any pressure and my pump keeps turning on and off when waters on does that mean tank is bad


If it's an internal bladder type tank I suspect the bladder has collapsed and stuck to the tank bottom preventing water entry. Otherwise, depending on where the pressure gauge is found, I'd expect to see at least some pressure in the tank. If your tank has a schrader valve (lkooks like a tire valve) near the tank top check there for pressure and also for water squirting out (which woul d usually mean a burst bladder.

Question: how do I get an accurate pressure reading on my Well-X-Trol tank?

(Dec 18, 2015) Tom ramsay said:
Pressure in tank (wellex-trol) is 40 lbs. But how do I get an accurate reading?


Accuracy depends on the quality of your pressure gauge; connect your hand held pressure gauge to the pressure valve (Schrader valve = looks like a tire valve) found on the tank (if there is one) or on the tank tee (if there is one).

If there is no Schrader valve present you'd need to install one at a suitable tapping on the tank or tank tee or on water tank piping.

Keep in mind that you will not see the same pressure at each measurement if the building water system is in active use since water leaving the tank will lower the pressure while water entering the tank will increase it.

Question: tank pressure setting versus tank pressure rating

(Dec 24, 2015) Mike alexander said:
How much pressure should a 100 psi tank have.


Mike I'm not sure what specification you're citing. If you mean a tank is rated for a maximum pressure of 100 psi that is only an upper safety limit. The water pressure tank operating range is set by the pressure control switch on/off pressures, typically 20/40, 30/50 psi, sometimes as much as 40/70 psi tops.

Question: only very low pressure seen in the pressure tank

(Jan 8, 2016) Thomas said:
I have a WX 202 Wel Tron Bladder Tank. I had to clean the jet nozzle on my FW Pump and drained the tank. The pump is unhooked from the well - the nozzle on the the pump was repaired - I benched tested the pump at 30 to 50 psi. The pump is hooked up to the well and tank. The tank is empty - the pressure check is barley 2 psi. Is that normal or should it be 30 psi or does this mean my bladder tank is not functioning correctly? Please note: I tried to put air into Bladder Tank and it will not inflate.



I suspect that water is not entering your pressure tank or the pump is not delivering water - check the pump prime.

If the pump is delivering water I suspect that water is not entering the pressure tank. The tank bladder could be stuck across the tank inlet. Some plumbers slightly boost the pressure temporarily to try to "open" a stuck bladder.

Watch out: do not attempt to use high air pressure at the water tank's air adjustment valve to force water out of a water pressure tank that uses an internal bladder. Doing so can rupture and destroy the bladder and worse, it can burst the water tank injuring or even killing a bystander.

Question: what should be the air charge in an empty pressure tank?

(Jan 8, 2016) Thomas said:
The tank Will Fill When I Turn On the pump. I want to know is should it have 30 psi in it now as it is empty. Only I tried filling it with air and it will not build any pressure in the empty Bladder Tank.


Thomas, when the pressure tank has no water in it at all its pressure can be set to 2 psi below the pump cut-in pressure

Question: pressure drops very quickly when the pump turns on

(Mar 2, 2016) Anonymous said:
I have a newly installed pump and pressure switch. The pump turns on and builds up to pressure but, then pressure drops quickly and the pump turns back on. Sometimes it will not turn back on when the pressure drops and the pressure switch does not turn it back on. Any solutions as to what needs addressed or changed?


IF pressure is falling rapidly either water is running or there is a leak or there is a failed check valve or foot valve allowing water to run back into the well.

OR the tank is waterlogged - when there is no air charge the water pressure will indeed fall almost immediately when you turn on water. That will turn on the pump. The short-cycling effect can burn up the well pump or switch.

Question: livestock water system pressure drops after the pump stops and no water is running

(Mar 9, 2016) Mike said:
My pump provides water to a livestock water trough. When the trough is full and the float valve in the trough shuts the water in the trough off. The pump pumps up pressure to about 50 PSI and then shuts off. Then then pressure immediately drops to 28 PSI and within a few minutes pressure continues to drop to about 24 psi and the pump kicks back on. Why does the pressure drop so quickly when the pump stops? What do I need to do to keep the pump from cycling so often?



Look for a failing check valve, bad foot valve in the well, or a hole or leak in well piping, OR a leak on the supply side of the pressure tank. Search for WATER PUMP INTERMITTENT CYCLING for more examples.

Question: what causs the water pump to keep turning on and off?

(Mar 15, 2016) Anonymous said:
What causes pump to turn on and off consistently



Please search InspectApedia for and read these two articles



Question: pump doesn't give enough pressure

2016/04/17 Jimmy said:
I can turn my outside faucet on and turn the pump off, when the water stops draining from hose i have 30 psi on my tank.

When i turn the pump back on my water pressure in the house drops when taking a shower, about a half of what it starts out with. Do i need to drain all the water out of the tank and put air back in it? The tank does not have a drain on it to drain the water out.



Indeed if your water pressure tank is waterlogged you need to correct the air charge. If it's an internal-bladder type tank that should not be the case but if the tank does not use an internal bladder you may need to add air.

If the pump cannot reach cut-off pressures in the 30-50 psi range then see WATER PUMP WONT STOP RUNNING

Readers of this document should also see WATER PUMP REPAIR GUIDE an specific case which offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost. The page top photo shows the author testing the air pressure in a Well-X-Trol bladder type well tank.

Watch out: these WATER TANK PRESSURE ADJUSTMENT instructions are for an un-damaged water pressure tank that uses an internal bladder. Reader Robert Ford pointed out by comment (17 Sept 2015) that if the internal bladder in the pressure tank has a leak or has burst you will probably have difficulty getting the water to drain out of the pressure tank. However his suggestion of using air pressure to force water out of the tank was not correct and could be dangerous.

Watch out: high pressures can burst the water tank bladder. Exposing the water pressure tank to excessive water pressures can also burst the water tank's internal bladder. Sometimes a water tank bladder sticks to itself, preventing water from entering the water tank and causing well pump short cycling. We might un-stick the bladder by slightly and just temporarily over-pressurizing the tank by say 15 psi but we should never exceed or really even approach actual pressures close to the water tank's rated or safe operating pressure. Typical maximum operating residential water pressures run between 20 psi and 70-80 psi. Higher pressures cause leaks and can burst the water tank or water piping.


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